| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high-capacity lithium ion secondary battery having a positive electrode with an active material density of 3.65 g/cm<SP POS="POST">3</SP>or higher, and offering excellent rate characteristics and cycle characteristics. <P>SOLUTION: The lithium ion secondary battery includes a positive electrode, a negative electrode, a porous insulating layer intervening between the positive electrode and the negative electrode, and a nonaqueous electrolyte impregnated into the porous insulating layer, and the positive electrode includes a positive electrode substrate and a positive electrode active material layer attached thereto, the positive electrode active material layer contains a mixture of a first active material and a second active material, the first active material contains secondary particles P1 with an average particle size D1, the secondary particles P1 are sintered bodies made from a plurality of primary particles p1 with an average particle size d1 satisfying 0.5 μm≤d1≤2 μm, the second active material contains secondary particles P2 with an average particle size D2 satisfying D2<D1, the secondary particles P2 are sintered bodies made from a plurality of primary particles p2 with an average particle size d2, the internal porosity of the secondary particles P1 is in the range of 3% to 10%, and the active material density of the positive electrode active material layer is equal to or higher than 3.65 g/cm<SP POS="POST">3</SP>. <P>COPYRIGHT: (C)2013,JPO&INPIT |
